Telephone system



May 10 1927.

H. M. FRIENDLY TELEPHONE SYSTEM Original Fi ed Jan. 24. 1921 5 Sheets-Sheet 1 UEPEEPH E 1'12 fg.

@M W my;

May 10 1927. 1,627,843

, H. M. FRlENl JL Y TELEPHONE SYSTEM Fi ed J 1921 5 Shets-Sheet 2 Fig-5 1,627,843 May 10 1947- M. FRIENDLY TELEPHONE SYSTEM 1921 5 Sheets-Sheet 3 y 10 1927" H, M. FRIENDLY TELEPHONE SYSTEM Original Filed Jan. 24. 1921 5 Sheets-Sheet 4 May 10 1927.

' 1,627,843 H. M. FRIENDLY TELEPHONE SYSTEM Original Filed Jan. 24. 1921 5 Sheets-Sheet 5 I [II l WYM Hil s.

Patented May 10, 1927. I

HERBERT MI. FRIENDLY, OF CHTCAGO, ILEINOIS.

TELEPHONE SYSTEM.

Application filed January 24, 1921, Serial No. 439,459. Renewed October 27, 195126. 1

The present invention has for its broad so-called twowire common battery automatic telephone system as has been widely used, the present invention necessitating novel departure from equipments heretofore known, in attaining the. new objects,'while retaining certain operative functions which are known.

Code-calling, as generally practiced and understood, contemplates a plurality of elect-romagetic signal gongs or other sounding devices located at various points throughout an establishment. A central code-controlling or code-transmitting device is provided, usually located convenient to the telephone attendant. Various persons connected with the establishment are assigned certain code calls, consisting ot'a seriesof the signals; these signals being made on the said sound-. ing devices, locatedsothat they may be audible from all parts of the establishment.

Thus, if it is desired to gain communication with any one of the'parties having a codecall and he cannot be reached directly on his telephone, perhaps, the call-attendant will set the code-transmitting device to sound his code-call throughout-the establishment. He will then respond in person or where local telephone service is available, call in to the operator from the most convenient telephone. Such a system in general but not interlinked with a telephone system is set forth in U. S. Letters Patent to Thompson No. 1,199,023, granted September 19, 1916.

Another adaptation of the so-called codecalling has been employed solely as an adjunct to private automatic exchange equipments, wherein the installation of such equipment includes devices, whereby any person at a telephone may call a predetermined telephone number (by dial) and thereafter annex a designated number referring to the code-call of a desired party, whereupon the code-calling will be automatically sounded throughout the establishment in a manner generally similar to that contemplated in the-said cited patent, where in the code-transmitting device is set manually by an attendant.

Where the code-transmitting device has been set functioning by a calling party dialmg as hereinbefore referred to, said calling party has been obliged to hold the telephone receiver off the switch-hook awaiting the re- Spouse of the called party. The called party upon hearin his code-call removes the receiver from .t, e switch-hook of the most con- .venient telephone and dials a predetermined number, whereu on he gains connection with the first sai pro-determined line, held by the calling party.

From the foregoing general description it will be perceived that heretofore codecalling'has had two forms; one manually controlled by an attendant, and the other automatically controlled by the calling party from his telephone.

'The present invention, among other objects, contemplates organizing in one system equipments having the advantages accruing to the two said general types of code-call equipments. That is to say, an attendant may transmit the code-call by suitably setting the code-transmitting device, or any party may transmit the code-call, controlled by dial from his telephone; the same codetransmitting equipment being employed under either conditionf In carrying out such a plan of operation, as contemplated herein, it is, of course, essential from an operating viewpoint to prevent interference between those desiring to transmit a code-call, for it must be borne in mind that all users will operate independ-- entlyand without knowledge of the other.

A condition presents itself under the contemplated plan of operation wherein the called party, upon hearing his code-call will not know whether he is sought by the attendant or sought directly from one of the telephones in the system. However, as will appear presently, provisionis made so that the party responding to a code-call will,

upon removing the telephone from the switch-hook of a convenienttelephone, al-

ways call a predetermined telephone number, which as will appear (in the present eXampled system), will be telephone number 28 whereupon if the code-call had been transmitted by a manual setting of the codetransmitting equipment by the attendant, the receiving telephone at the attendants cabinet will be rung and the attendant may then eitheranswer the code-called party in a the usual manner by removing the receiver lltli from the switch-hook, or if the attendant has switchboard equipment may respond by inserting an answering switching-plug into a spring-jack connected to the said receiving telephone. However, had the code-call been initiated by a party at one of the exchange telephones calling the predetermined numher (which in the present exampled system, will appear as number 39), and thereafter annex the number indexing the code-call for the desired party, upon the latter party responding as before by calling telephone number 28 he will place himself in direct telephonic communication with the calling party at the exchange telephone in lieu of reaching the attendants receiving telephone. Referring to this function more generally, it may be stated that if the code-call has been initiated by a party calling from a telephone, setting up the code condition through the agency of one of a plurality of code-connectors, the responding party upon calling a predetermined responding number from a convenient telephone will be automatically directed to the code connector to which the calling party is connected. If the code calling has been initiated from the attendants switchboard, and not through a code-connector, the answering party will be automatically directed to the attendants telephone.

A further novel function contemplated under the present invention, is that which permits the party initiating the code-calling from a telephone to replace his receiveron the switch-hook at any time after initiating the code-calling and before receiving a response' from the called party, and upon the code-called party responding by calling telephone number 28, the telephone from which the code calling was initiated will be rung so that the calling party thereat can respond and be incommunication with the said called party, who responded first. It is thus manifest that the calling party is not obliged to retain the telephone off the hook awaiting the response (or non-response) of the called party.

Code-calling initiated from a telephone will be sounded not more than a predetermined number of rounds after the calling party initiates the code-calling, provided the calling party hangs up before the predetermined number of rounds has transpired, and

not more than the predetermined number of times after the calling party hangs up, if no response from the called party is obtained. This is to prevent an indefinite number of rounds of the code, which may be annoying if no response by the called party is obtained. However, the calling party .can terminate the sounding of the code-call at any time by rnomentarily removing the telephone from the switch-hook after he has replaced it. The latter function, provided mamas a response has not been obtained from the called party, will restore the calling partys telephone line (and interlinked switches) to normal condition forthwith and, therefore, ready for normal outgoing or incoming service.

Heretofore, so far as I am aware, when a code-call has been initiated, controlled from a telephone and has been responded to,

no other code-call could be transmitted until after the code-call transmitting equipments have been released by both the calling and the called party terminating the service by hanging up.

The present invention provides that as soon as the called party has responded, or that the rounds of the code have been terminated as hereinbefore referred to by the calling party again removing his receiver from the switch-hook, before a response has been obtained, the code-equipment is available to others who may desire to use it after the code-transmitting device thereupon restores to normal, as will appear. ent exampled system contemplates that two parties calling from telephones may hold conversations with parties called by code while the attendant may be transmitting a code-call and receive a response from a third code-calling.

The system contemplated in the present invention, of course, provides for guarding the code-calling equipments against seizurewhile a code-call 'is being transmitted and also while the code-transmitting device is in an off-normal state to prevent possible confusion, and under such conditions, an attempt to initiate a code-call will result in the calling party attempting to initiate such codecall receiving the usual busy condition sig nal.

Referring to the accompanying drawings:

Fig. 1 shows a calling telephone leading to a preselcctor in access to a plurality of 1 connectors, one only of which is shown.

Fig.2 is an abbreviated schematic representation of an equipment like Fig. 1, which attaches above Fig. 1 so the lines running towards the margins register,

Fig. 3 is a code-connector, which attaches to the right of Fig. 2, so the lines extending towards the margins register.

Fig. 4: is a code-connector, being a slight modification of Fig. 3, and co-operates with it, and which attaches to the right of Fig. 1 and below Fig. 3, so the lines extending towards the margins register.

Fig. 5 which attaches to the right of Fig. 3 so the lines extending towards the margins register, isa schematic representation of the code transmitting equipments adapted to be controlled by Figs. 1, 2, 3 and 4.

To simplify the drawings and descriptions, the battery (which has its negative pole grounded) and ground are shown as in The pres-' dependent sources throughout, Wherever applied, but it is to be understood that the syssidered as traced to ground through the winding and battery or direct to ground, as indicated.

' Referring again to the various figures:

In Fig. l the calling telephone T (of which there are a plurality in the system) is of the usual series type, having a sending device of the general class, as shown in British patent to Dicker, No. 29,654 of 1910. The pre-selector (also called a lineswitch) PS is of the general class, as shown in U. S. patent to Lamb, No. 1,193,160, granted August l, 1916. Theconnector A is'of the general class as set forth in U. S. Letters Patent to Deakin No. 1,164,479, granted December 14, 1915. However, the connector designated A of the present invention contemplates'new objects along with those Well known. The said connector A is arranged for discriminating service, the telephone, line leading from pre-selector PS to telephone T' being non-restricted. The set of off-non inal contacts 3 is adjusted to close upon the shaft reaching the 10th level, and bank contact positions 28 and 29, and bank contactposition 39 and beyond (on the same level). The set of off-normal contacts-4 is adjusted to close upon the shaft reaching the 9th level and bank contact positions 28 and 29, and bank contact position 39 and beyond. The set of off-normal contacts 5 is adjusted to close upon the shaft reaching bank contactposition 28 and 29, and bank'contact'position 39 and beyond. The connector A is designed to function as a. selector, the telephonic conductors of which will be clear of battery and ground attachments on the 10th level and also at bank contact positions 28, 29, 39 and 30; as a selector with battery and ground supplied to the telephonic conductors leading to in and out lines supplied through the frontbridge and back-bridge relays on the 9th.

level, and as a connector with battery and ground supplied over the telephonic conductors to in and out lines, through the front and back-bridge relays on all other levels and bank contact positions. Off-normal contacts ON are adjusted to close upon the shaftstepping from normal. The set of springs designated 11th rot (and which may be termed eleventh-rotary springs) are designed to operate upon the shaft moving beyond the'10th rotary position at any level. V

It is usual to'h. a connector of types as heretofore used to cooperate with bank contacts of which there are 10 sets or rotary lar to telephone T in Fig. 1.

positions per level and of which there are 10 levels. The contacts shown at the right of Fig. 1 are assumed to be the last three sets of contacts of the'lst, 2nd and 3rd levels of such a group of levels, respectively.

In Fig. 2 the calling telephone T2 is simi- The preselector PS2 is similar to PS in Fig. 1. However, the one point of dissimilarity in Figs. 1 and 2 is that the line'leading from telephone T2 is restricted against obtaining service on the 0 level. This is by virtue of the contact 6 of the cut-off relay of the pre-selector PS2 being ungrounded. The dotted square designated A2 represents a connector like the connector A shown in Fig. 1. The bank contacts shown in Fig. 2 are in multiple relation to contacts in Fig. 1 corresponding in position. There would usually be a number of connectors similar to A having their respective bank contacts in multiple relation.

The connector Fig. 3 belongs to the general class, as shown in U. S. Letters Patent to Keith & Erickson No. 815,176, granted March 13, 1906, of course, modified in mechanical and circuit details to operate on the Well known so-called two-wire principle and to embody the present invention. A salient feature of novelty in this connector is the fact that it is permanently related to an outgoing line and that it has a set of wipers which are adapted to cooperate with sets of bank contacts of the stated type, but that these contacts are Wired in such disposition that they will control a code-transmitting mechanism as shown schematically in Fig. 5 and which will be detailed presently. The bank contacts shown may be assumed to be the first four sets of the first level, it being understood, of course, that usually there would be perhaps ten sets of .contacts per level and that there would be inafter, and the cited patent to Thompson,

that a greater number of codes than ex ampled may be readily applied by adding more sets of contacts to the level and by employing contacts on a plurality of levels.

It will appear presently (and as heretofore adverted to) that the code-connector Fig. 3 includes the function of not only ringing upon its leading-out line, but also will ring back upon its leading-in line, as well as other novel features, as will appear.

In Fig. 5, 501 is a rotatable contact-arm, shown as 20 in the cited patent to Thompson, and is adapted to rotate to the right, successively engaging contacts 502 to 506 (inclusive) and then reengaging the said of the arm 501 (shown in normal position),

bearing in mind that the arm 501 is designated to rotate completely a plurality of times.

Contact plates 507 to 512 correspond to the plates shown in Fig. 9 of the cited patent to Thompson and fully described therein. However, the wiring disposition of the plates is changed to conform to the presentinvention. Sufiicient to example here that if conducting plug 513 is inserted into the first position indicated by dotted line 514, plates 507, 508 and 512 will be electrically joined, and plates 509, 510 and 511 will be free so far as plug 513 and plates 507, 508 and 512 are concerned. Should plug 513 be inserted into the third position indicated by dotted line 515, plates 507, 508, 510, 511 and 512 will be electrically joined, and plate 509 will be free with reference to these latter plates.

Ge represents a. direct current supply source and M represents a motor designed to drive the arm 501. 516 and 517 are bells or electromagnetic gongs susceptible to the current projected from the source Ge. Usually there will be a larger plurality of such bells located at various parts of the establishment. At the upper right hand cor- .ner of Fig. is a step-by-step mechanism S carrying a grounded wiper 521 which engages the contacts 522 to 526 successively, driven by the magnet D5; the latter magnet, operating ratchet-pawl 527, steps the wiper 521, which is rigidly attached to ratchet wheel 528, one step for each energization of said D5. Retaining-pawl 529 pivoted at 530 is tensioned against the edge of the ratchet-- wheel 528. A. spiral spring (not shown) has one of its ends secured to the mounting frame of D5 and one of its ends to the ratchet wheel 528, so that when the retaining pawl 529 is attached by release magnet Ref) the wiper 521 and attached ratchet- ,wheel 528 will be returned to normal. A spiral spring for restoring a shaft to its normal rotary position is shown in the cited patent to Keith and Erickson. @ff-normal springs 0N5 engage at all off-normal positions of wiper 521.

Lamps 531 to 53 1 correspond to the plug positions indicated by the dotted lines 514, 515, 535, and 536, as also do lamps 537 to 54-0- as will be manifest presently. The lamps 531 r0534 are controlled by connector Fig. 3, and, glowing designate the engaged position of the wipers of the said connector.

The lamps 537 to 540 are controlled by Fig.

. I I 4, and, glow1ng desigpate the engaged posn tions 01 the wipers Or the said connector.

The operation of the system contemplated under the present invention will be clearly mamas understood from the following description of its operation under the several assumed conditions.

It is to be understood that the connector A in Fig. 1 (and similarly A2 in Fig. 2, and other similar connectors not shown but which will be referred to) has access to a plurality of exchange telephones, as for example, T and T2, through bank contacts 12,

13, and 1 1 to telephone T, and 15, 16 and 17 to telephone T2. This is in addition to the auxiliary feature of the code-call, which auxiliary feature forms one of the salient features of the present invention. For that reason the operation of the connectors shown in Figs. 1 and 2 will not be detailed in connection with local telephones under ordinary exchange service' conditions, nor with their operation in obtaining access to trunk lines on the 9th and th levels whereat the connectors will respectively function as a selector, as contemplated in the cited patent to Deakin. mind that the connectors function somewhat differently as a selector on the 9th level than on the 10th level, in that the battery is supplied from the back bridge relay of the connector to the line wipers 18 and 19 (in connector A) when the switch is functioning on the 9th level, and that this'battery is not so applied when the switch is functioning on the 10th level.

Assume that party at telephone T desires to summons the party having code-call of three strokes of the gongs, as shall be hereinafter referred to as three bells. Upon removing the receiver from the switch-hook to initiate the call the pre-selector PS will seize the trunk leading to the idle connector A. A. circuit may now be traced from battery, upper winding of relay N, conductor 20, spring 21, conductor 22, pro-selector wiper 23, conductor 24:, through the telephone T, conductor 25, preselector wiper 26, conductor 27, contact 28, conductor 29, lower winding of relay N to ground. Relay N will actuate, applying ground from armature 32, armature 34, contact to winding of'slow-releasing relay B, causing relay B to actuate. Ground on contact 30 will be applied through armature 31 to conductor 33 and to the winding of the actuated cutoft relay of the pre-selector PS, thus main t aining it actuated in the well-known manner. The calling party will operate the calling device 2, transmitting digit-s 3-9-1-3. The transmitting of the first digit 3 effectuates three open impulses, causing relay N to deactuate and reactuate three times, transmitting ground impulses from armature 34. contact 36, side-switch wiper 37, winding of slow releasing relay C through vertical magnet V and through side-switch wiper 38 to battery. This will cause the shaft of the connector to be raised three vertical steps,

However, it is to be borne in I its wipers-registering in line with the third levels of bank contacts.- Consequent to the first of three current impulses traversing the winding of relay C, its grounded armature 39 will engage contact 40 and energlze I the private magnet P, causing it to actuate and so remain throughout the series.' Upon the cessation of theseries'of the three impulses relay C deactuates its period thereafter and allows the armature ofwthe private magnet P 'to retract and permit the sideswitch wipers 37, 38 and 41 to advance 1nto their second positions respectivel Upon the second digit 9 being transmitted, constituted of nine open impulses, the described functioning of relays N and C and the private magnet will again ensue. However, due-- to the side-switch wiper 38 now being in the second position, the described circuit oath through relay C to conductor 42 will be continued through armature 43, conductor 44, winding of rotary magnet B, sideswitch Wiper 38 to battery. The rotary magnet will operate nine times responsive to the said current impulses and rotate the shaft carrying the wipers 19, 18 and 45 into engagement with bank contacts 46,47 and 48 respectively. A well known mechanical connection exists between the armature of rotary magnet R and the armature of private magnet P, whereby each attraction of the armature of the rotary magnet causes the armature ofthe private magnet to be moved as if it were acting under normal energlzation of the private magnet.

Assume that contact 48 constituted bat- V tery potential and, therefore, its companion contacts 46 and 47 and attachments are nonbusy and seizable, and bearing in mind that upon the retraction of armature39 of relay C following the last impulse of digit 9 the private magnet deenergized and its armature re'tracted and permitted the advancement of side-switch wipers 37, 38 and 41 to their-respective third positions, a circuit can now be traced from battery through the resistance 302, conductor 30'1, conductor 201, bank contact 48, wiper 45, side-switch wiper 41, inside-winding of relay H, contact 49 ofprivate magnet, conductor 50, conductor 51, upper armature of relay B, wiper 52 of preselector to grounded contact 53 on the cutoff relay in the pre-selector. The relay H will actuate, and will lock as will be hereinafter detailed. I

In this connection it is to be borne in mind that under the assumed operative condition, off-normal contact sets 3, 4, and 5 i are operated. Thus, a circuit willensue from batterythrough relay D toground on spring 54, and a supplemental ground will alsobe applied to conductor, 51 through oftnormal set 5 by wayof upper armature of relay-B. However, had the station'T (like T2) been a restrictedstation, denied'access preselector PS and therefore, the supplemental ground will be operatively applied to conductor 51 through off normal set 5. Re-

lay H will actuate energized over the described circuit. It is manifest that had wiper 45 not found battery potential on bank contact 48, an energization circuit for relay H would not have been established after the side-switch wipers 37 38 and 41 moved into their respective third positions, and the rela H would, therefore, remain inert. Underthe latter condition a circuit would be established from ground on contact30 of relayB (relay B being actuated) armature 31, conductor 33, contact 57 on relay H, conductor 58, side-switch wiper 37, winding of relay C, outside winding of relay J, sideswitch wiper 38 to battery. Relay J will actuate and remove ground from armature 34, thus preventing movement of the switch shaft should the sending device 2 be manipulated. Relay H being normal, no telephonic circuit will be established to the wipers l9 and 18.

Had bank contact 48'constituted ground potential by reason of one ofits multiples, as 59, being in a seized condition by wiper 60 of an assessibleconnector, A2 for example, when the wiper 45 engaged it and after relay C deactuated, a circuit path would be established from said grounded contact 48, wiper 45, side-switch wiper 41 (in second position) armature 61, contact spring 40, conductor 62, winding of private magnet P,

' causing said P to remain energized, thus preventing the said side-switch wipers from moving 1nto their respective third positions.

Relay J now being normal, due to the sideing the rotary magnet energizing circuit,

and allowing the rotary magnet to deenergize and restore, followed by dependent re-- lay J, whereupon the circuits are in the condition as-in the exampled instance when wiper 45 engaged. bankcontact 48 after relay .C deactuated.

Assume further that bank contact 64 also constituted ground potential (the selector shown in Fig. 4 being engaged) then the [same circuit condition will assume as when relay C deactuatedafter wiper 45 engaged bank contact ,48, when assumed asconstituting ground potential, so the rotary magnet will again function and drive the shaft a rotary step, a shaft-cam engaging and operating the 11th rotary cam-spring -set.

The wipers, 19, 18 and being now free of the bank contacts, after relay G deactuates, an inert circuit path can be traced from battery through resistance 65, conductor 67", side-switch wiper 41 (in second position), armature 61, contact-spring 40, conductor 62, Winding of private magnet P to battery. The private magnet will thus not be energized now and will retract, following the deactuation of relay C, allowing the sideswitch wipers 37, 38 and 41 to advance into their respective third positions, whereupon the battery traced throughresistance 65 to side-switch Wiper 41 will be applied through inside winding of relay H, contact 49,.conductor 50, upper armature'of relay B, 0&- normal contact set 5 (also to grounded contact 53) to ground, causing said relay H to actuate and look its outside winding through contact 66, armature 67, conductor 33, armature 31, to grounded contact 30. A circuit can forthwith be traced, before relay B can' deactuate, as relay K will actuate because of the establishing of a circuit from its winding through off-normal contact set 3, conductor 70, contact 71, contact 72, armature 67 conductor 33, armature 31, to grounded contact 30. Also, a circuit can forthwith be traced (before relay B can deactuate, as will appear) from battery through resistance 73, conductor 74, winding of relay G (and its shunt), armature 75, conductor'76, contact spring 21, over the describedpath through the telephone set T to armature 77, conductor 78, contact 79, to grounded resistance 81. Relay G being operatively energized over this circuit path, causes a ground to be applied to the winding of relay B from grounded armature 82 and conductor 83 (before relay B has had time to deactuate due to its primary relay N deactuating because of being disassociated from conductors 22 and 27 consequent to the described actuation of relay K), maintaining ground on conductor 33 through armature 31 and contact 30.

Ground-seeking tone-source TS is applied to the free side of resistance 81 and will convey an audible tone to the calling party holding telephone T, over the described path including resistance 73. The calling party being thus apprised that both the code-connectors Fig. 3 and Fig. 4 are busy, will replace the receiver on the switch-hook and terminate the service, whereupon relay G will deenergize and deactuate, followed by dependent relays B, H and K. An operative circuit will now ensue from the lowermost armature of relay H, winding of the release magnet Re, oH-normal contact spring 84, armature 85, armature 34, to grounded armature 32. Upon the release magnet Re operating the switch shaft will be restored to normal, andrelay D will be deenergizedand restore. 1

Going back to the assumed condition of bank contact 48 constituting battery potential as it does normally) when first engage by wiper 45 and after relay H actuated, a lOCkIII circuit is formed from outside winding of relay H, contact 66, armature- 67, conductor 33, armature 31, to grounded contact 30. Also, ground on armature 67 is applied to contact 86 through sideswitch wiper'41, wiper 45, bank contact 48, conductor 201, conductor 301 to the free terminal of resistance 302. Thus, the battery potential primarily existing, upon bank contact 48 and bank contact 59 (and its multiples) is changed to ground potential,

guarding them from subsequent seizure by an accessible connector as A2, for example.

A circuit may now be traced from the upper winding of relay 303, conductor 304, conductor 305, contact spring 306, conductor 307, armature 308, conductor 309, conductor '202, bank contact '47 Wiper 18 winding of shunted relay G, armature 75, conductor 76, contact spring 21, over the described circuit path including telephone T to armature 77, conductor 78, contact 79, wiper 19, bank contact 46, conductor 90, conductor 91, contact 311, contact 312, conductor 313, conductor 314 to the lower winding of relay 303. Re-

lay 303 will actuate applying grounded armature 315 to contact 316 and to the winding of slow-releasing relay 317, causing it'to actuate. I

Upon the calling party sending the third digit 1 by manipulating the sending device 2, in accordancetherewith, the circuit including the windings of relay 303 will be opened one time, causing armature 315 to retract against contact 318, and apply ground to contact 319, conductor 320, armature 321, conductor 322, winding of slow-releasing relay 323, winding of vertical magnet V3, side-switch wiper 324, to battery, causing the said vertical magnet to actuate and move the shaft of the code-connector Fig. 3 one vertical step. When relay 323 Was energized its grounded armature 325 applied ground to the winding of private magnet P3, causing it to attract its armature. Upon the deactuation of relay 323, its period after the cessation of the current energizing the vertical "magnet, the private magnet is deenergized, allowing its armature to retract, permitting the side-switch wipers 324 and 326 to advance into their respective second positions. Upon the party at the calling telephone transniittiinq; the fourth digit 3 by manipulating the sending device 2 in accordance therewith, relay 303 will deact'uate and rea'ctuate three times responsive to the series of three impulses constituting the digit 3, applying three grounded impulses over the before described circuit path from grounded ar- Inn mature 315 through the winding of relay 323. However, this time to the winding of the rotary magnet R3, side-switch wiper 324 to battery, causing the rotary magnet (and relay 323 to attract as before) to operate three times and rotate the shaft carrying wipers 327 to 331 three rotary steps and into engagement with bank contacts 332 to 336 respectively. Upon the cessation of the-said series of three impulses through the winding of relay 323 and its armature retracting,

causing the private magnet to in turn retract permitting the side-switch wipers 324 and 326 to advance into their respective third positions, a circuitpath as follows will ensue: battery on side-switch wiper 324,;conductor 337, winding of relay 338, side-switch wiper 326 to ground, causing relafy 338 to actuate. Grounded armature 339 will apply ground to wiper 331 and its engaged bank contact 336, conductor 340, through lamp 533, to' battery, causing the said lamp to glow, indicating to the attendant that codeconnector Fig. 3 is transmitting a code-call and that the code-call being transmitted is three bells as indicated by the glowing of the said lamp 533. Grounded armature 341 applies ground to contact 342 and to the wind ing of relay 343 causing it to actuate. A cir- 39 cuit may now be traced from conductor 344 to wipers 327 to 330. Grounded armature 345 applies ground to contact 346, conductor 347 and to the winding of relay 541, causing it to actuate. Bearing in mind that the plus pole of current source Ge is common to the plus terminal of the motor M, a circuit may now be traced from the minus pole of current source Ge, conductor 542, armature 543, conductor 344 and its attached wipers 40 327 to 330 in engagement with bank contacts 323 to 335 respectively. A circuit may also be traced from armature 543 'over conductor 544, contact 545, to the minus terminal of motor M. Thiswill cause motor M to be energized and start its rotation, and rememberi ng that the motor drives the contact arm e 501, and that the said arm upon, startingits rotation successively engages contacts 502 to 506, and that upon the oft-normal movement of arm 501 the sets oflcontacts constituting off-normal set 0N5 engage respectively, a circuit may be traced from the plus pole of supply source Ge through winding of relay 546 to arm 501. -From the fact that the wipers 327 to 330 are engaged 'to bank contacts 332 to 335 respectively a circuit path exists from the minus pole of the supply source Ge over conductor 542, armature 543, conductor 344, wiper 329, bank contact 334, conductor 348 to contact 503. Also, from c'cinductor 344, wiper 328 bank contact 333 conductor 349 to contact 504. Also from conductor 344, wiper 327, bank contact 332,

conductor 350 to contact 505. Thus, as arm 501 in its rotation successively engages the source. Each time this circuit-is completed the relay 546 will become energized and close a circuit from the minus pole of supply source Ge over conductor 547 through the windings of the gongs 516 and 517 in multiple to conductor 548, armature 549 to conductor 550 and to the plus pole of the supply source Ge.- The gongs will sound responsive to each of the three actuations of relay 546, consequent tothe arm 501 engaging the contacts 503 to 505. It is to be borne in mind that bank contact 335 is free and that there is no continuity between contact 502 and conductor 344.

As arm 501 engages contact 506 following the disengagement of the last code operative contact 505, a circuit may be traced from the minus pole of the supply source Ge over conductor 547, through the drive magnet D5, conductor 551, armature 552, conductor 553, contact 506, arm 501, winding of relay 546, conductor 550 to the plus pole of the supply source Ge, causing the drive magnet D5 to attract resultant thereto and step the wiper 521 into engagement with dead bank contact 522. Consequent to the energization of the latter described circuit, relay 546 will close the described circuit including the windings of the gongs 516 and .517. Contact 506 being located very close to bank contact 505 will cause the last bell of the code series to be followed by a supplemental stroke at a .very short interval thereafter, indicating to the auditors that the end of the code has transpired, and therefore, it will not be confusing where codes may consist of different ly spaced strokes of the gongs.

Assume no response will be made by the called party, the arm 501 will continue rotating and successively engage the contacts 502 to 506 until five impulses havebeen imparted over the described path, including conductor 553,, and therefore, the drive magnet D5 has caused the wiper 521 to enga e the fifth bank contact 526. A circuit may'%e traced from groimded wiper 521, bank contact 526, conductor 554 to the winding oi release magnet Ref), causing said release magnet to actuate, attracting the retaining pawl 529- from ratchet-wheel 528, causing the latterand its attached wiper 521 to restore to normal due to the influence of the retractile spring shown attached to the ratchet wheel. At the time release magnet Re5 is energized multiplied relay 555 is energized and actuated. The purpose of this said relay will be detailed presently. Due to the fact that relay 541 is only energized from one of the connectors, as Fig. 3 or Fig. 4, (and not through the agency of plug 513) as will be manifest presently, armature 552 will not be disengaged from its resting contact 556 under the conditions wherein the code transmitting device is controlled by the attendant through the agency of plug 513, (as relay 541 will be normal) and therefore, there will be no limit to the number of rounds of the code-calling which can ensue while manually controlled and supervised by the attendant. Under the latter condition, that of the codecalling being initiated by the attendant, relay 541 being normal, drive magnet D will be excluded from the operative circuits, the traced circuit path from conductor 553 now being diverted at armature 552 to resting contact 556, conductor 557 to conductor 547..

Thus, the drive magnet D5 will only operate when relay 541, controlled by a code-connector, is actuated. 3

It has been set forth that conductor 301 becomes grounded from connector A (or A2) at the time code-connector Fig. 3 is seized. A circuit can therefore be traced from grounded conductor 301, contact 352, conductor 353, contact 558, to the winding of slow-releasing relay 559, causing it to actuate, disassociating plates 507 to 512.

At the time arm 501 is moved off-normal, operating off-normal set 0N5, a circuit may be traced from conductor 542 through the lower set of springs of off-normal set 0N5 to the minus terminal of motor M. It will thus be clear that the terminals of motor M are thus connected to the corresponding poles of the supply source Ge, independent of the closure of the described circuit from conductor 542, armature 543, conductor 544, contact 545 to the minus terminal of motor M, by reason of the actuation of relay 541 at the time relay 343 actuated. It will be clear presently that should any condition arise whereby relay 343 would deactuate, as for example, by the calling party causing the code-connector Fig. 3 to be restored to normal, forthwith causing the relay 541 to deactuate and open the motor-start circuit including conductor .544, as described, the motor will continue revolving until wiper 501 reaches its normal position, wherein the lower set of springs of olf-normal set 0N5 will disengage and open the motor circuit. That is to any, complete rotations of the arm 501 only can be effected, even though the primary start motor circuit traced is opened before a complete code-call series has transpired.

It will be assumed, now, that after the operations of code-connector Fig. 3, including the actuation of its relay 343 as described, and further that the code-calling is transpiring, sounding series of three bells, the calling party restores his receiver on the hook-switch. not wishing to await the response of the called party. Relay 303 will 'deactuate, and its dependent relay 317 applies ground from lower spring of off-normenses mal set 0N3, spring 354, contact 355 to the winding of relay 356, causing it to actuate. A locking circuit for this latter relay will now exist from grounded conductor 301, conductor 357, spring 358, contact 359 to the winding of said relay 356. Under the present condition conductor 301 still receives ground from over the described path in connector A, and also from armature 359 in the code-connector Fig. 3, by way of spring 358, and conductor 357. However, due to the energized path described as including the calling telephone T and the relay G becoming open consequent upon the calling party replacing the receiver on the switchhook at telephone T, the said relay G (which is slow-releasing, due to the shunt winding thereon) will deactuate and remove ground from the winding of relay B, causing the latter relay to deactuate its period thereafter. associated from conductor 33 due to the retraction of armature 31 of relay B. Remembering that conductor 301 constitutes ground potential applied from lower spring of off-normal set 0N3, and that relay H was actuated and locked at the time armature 31 retracted, it will be clear the latter relay will be maintained locked from the ground received from the conductor 301 by way of contacts 86 and 66. While a circuit can now be traced from the grounded armature 32, armature 34, armature 85, offnormal spring 84 to the winding of the release magnet Re, the battery normally on its lower terminal is disassociated at the lowermost armature of attracted relay H, and therefore the connector A is incapicitated against releasing. That is to say,-if the leading-in test conductor 301 of code-eonnector Fig. 3 constitutes ground potential applied from within code-connector Fig. 3. when the calling party restores the receiver on the switch-hook at telephone T, the connector A cannot release and the telephonic circuit previously established to the leadingin line conductors of the code-connector Fig. 3 is maintained.

It will now be assumed that no response by the called party will be made. Then, upon arm 501 engaging contact 506 for the fifth time at the. end of the fifth round, wiper 521 will engage bank contact 526 and complete a circuit to the winding of the release magnet Re5, causing the wiper 521 and its attached ratchet-wheel 528 to be retracted to normal, and relay 555 to be momentarily actuated as has been set forth hereinbefore. A circuit can then be traced from the winding of the release magnet Re3, spring 360, armature 361, contact 362, conductor 363, grounded contact 560,'eausing the release magnet Re3 to actuate and restore the codeconnector Fig. 3 to normal.

The described circuit, including the wind Ground on contact is dis net armature 368, spring 358, contact 359.

contact 355, spring 354 to engaged grounded spring, and to conductor 301. Therefore, the release magnet upon actuating will become locked actuated until the said ground path is opened at spring 354. It will be re membered that under the now assumed condition, no ground is applied to conductor 301 from connector A, and in fact,'relay H is maintained from ground received from spring 354. It is now manifestthat upon t e shaft of the code connector Fig. 3

.restoring, not only will the release magnet Re3 restore, but also relays 356, 338, and 343, as well as relay H in connector A, whereupon the described path to the release magnet Re will be continued to battery on the lowermost armature of relay H, causing the restoration to normal of connector A.

Had the calling party not restored the re ceiver on the switch-hook, and five rounds of code-calls were allowed to transpire while he held the receiver off the switch-hook, awaiting the response of the called party, the restoring functioning of ratchet-wheel 528 when wiper 521 engages bank contact 526, and also the actuation of relay 555 would, as set forth, be coincident with the actuation of the release magnet Re5. However, the code-connector Fig. 3 would not be restored because armature 361 would be at normal, and therefore, no ground circuit from the winding of the release magnet Re3 over the described path to grounded contact v560 would be established. If the calling party would after the said release of ratchet-wheel 528, at the end of the fifth round restore his receiver on the switchhook, armature 361 of relay 356 would attract as before described and prepare the described releasing circuit to energize the release magnet Re3 at the termination of the second five rounds of bells.

Assume now, that While the code bells were being sounded the calling party for some reason wished to stop the code calling, bearing in mind that upon hanging upthe receiver on the switch-hook afterinitiating the code-calling, relay 303 and 317 deenergized and restored in sequence and that relay 356 actuated and locked. He would remove his receiver from the switch-hook (having previously replaced it upon the switch-hook after initiating the-code-calling) which would cause relay 303 to energize and. actuate, followed by relay 317.

The winding of relay G being in series with the windings of relay 303 it will energize and armature 82 will apply ground to the winding of relay B, so the condition in connector A is now as described upon its rcizure of code-connector .Fig. 3. However, as will appear, this condition endures for but a brief operative period.

A circuit can now be traced from thewinding of release magnet Re3, spring 360,

armature 361, armature 364,- to grounded armature 365, causing the. release magnet Re3 to actuate and restore the code-connector Fig. 3 tonormal. This restoration to normal will, of course, imply the deactuation of its actuated relays and the disassociation of its wipers 327 to 331 from engaged bank contacts, and also the deactuation of dependent relays in Fig. 5.

It has been set forth that the energizing circuit including the winding of relay G and the windings of relay 303 will be opened consequent to the release magnet Re3 actuating and attracting armature 307. Also, that the ground path from conductor 301 in code connector Fig. 3 will become opened consequent thereto. Under the stated condition relay G Will deactuate and dependent relay B will deactuate, removing ground from conductor 33. Relay H will deactuate. Relays N, B, J and Hv being now normal, the described releasing circuit including the release magnet Re will be completed and the connector A will be thereby released to normal. Upon the shaft of connector A retracting from its operated position the circuit described as including relay K will be opened, resulting in said relay K deactuating and establishing the windings of line relay N in circuit with telephone T as described at the outlet, as it the call into connector A were initiated at this time. It is thus clear that while normally connector A will release to normal when the calling party restores the receiver on the switch-hook at telephone T, this functioning is materially changed when the said connector A cooperates with a code connector, as Fig. 3, in that its release to normal now depends upon the release of the code-connector, whichas has been fully set forth, does not restore responsive to the rethe deactuation of relay 541, as will appear presently.

While relay 546 operates, transmitting code-impulses as described. armature 565 closes an inductive circuit, including resistance 566 and condenser 567 between conductors 369 and 370. Bearing in mind that while the code-call is transpiring and thecalling party has the receiver off the switch hook, relay 338 and other stated relays in Fig. 3 will be actuated, an inductive circuit path will be closed from generator G3, armature 371, contact 372, conductor 373, condenser 567, resistance 566, armature 565, conductor 374, armature 375, contact 376, inside-winding of relay 377 to battery, and from condenser 567 through ringer 567' to conductor 374. The interrupted current from source G3 traversing this circuit path will induce a tracing audible to the calling party, from battery, outside winding of relay 377, lower winding of relay 378, conductor 379, conductor 313, contact 312, contact 311, conductor 91 over the described path, including the telephone T to conductor 309, armature 308, conductor'307, spring 306, conductor 305, conductor 304, upper winding of relay 303 to battery. Thus, for every closure of relay 546, a brief tracing of greater intensity will be audible to the calling party and index that the code-call is transpiring normally. This would be of convenience where the gongs 516 and 517, for example, are located too remote to be audible to the calling party.

Assume that the called party upon hearing his code-call responds from a convenient telephone by removing the receiver from the switch-hook to initiate the call in a normal manner, and further assuming that this telephone is the one shown in Fig. 2 designated T2. The pre-selector PS2 will seize the trunk line leading to the connector represented by A2. The responding party will then manipulate the calling device 203 to operate the connector A2 in a manner as described with relation to telephone T and the connector A shown in Fig. 1 by the calling party at telephone T only in this instance the responding party will etfectute the calling of telephone number 28, (in lieu of telephone number 39) whereupon the wipers 60, 205 and 206 will engage bank con tact 207, 208 and 209 respectively.

(ioing back to the code-connector Fig. 3, it will be noted that normally ground potent ial exists on conductor 380, by way of contact 381.. contact 382 and grounded armature 365. but that when the code-connector Fig. 3 was seized by the connector A in Fig. 1, as described and relay 303 actuated this ground potential normally existing on conductor 380 is changed to battery potential by virtue of a circuit being completed from contact 381, contact 383, through resistance 384 to battery. It will also be noted that when the calling party replaces the receiver on the switch-hook allowing the code-calling to still transpire as set forth hereinbetore, and relay 303 deactuated and relay 356 actuated and locked, the battery potential was maintained on conductor 380 by way of contact 385, resistance 384 to battery. Thus, while the conductor 380 has ground potential on it normally, it has battery potential on it when its leading-in conductors are seized by connector A, but it will be clear presently that this is again changed to ground potential incident to the seizure of the leadingout conductors of the code-connectorby the connector A2, controlled as described by the responding party.

The object of having ground potential normally on conductor 380 is to maintain a guarding or busy condition on the leadingout conductors of the code-connector at bank contact 207 at all times, except when the code-connector is controlling a code-call. It will be manifest presently that this is primarily to constrain the connector as A2, operated by the responding party, from seizing bank contacts leading to a code-connector other than the one to which the calling party is connected, and also to insure that neither code-connector can be reached by a responding party if the code-call is under the control of the attendant, set manually.

A circuit can now be traced from the inside winding of relay 377, contact 376, armature 375, conductor 370, conductor 212, bank contact 209, wiper 206 through the connector A2, wiper 213 of pre-selector PS2, line conductor 214, condenser 218 and ringer 219 (218 and 219 shunted by the conductive path through the receiver) of the telephone T2, line conductor 215, wiper 216 of pre-selector PS2, through the connector A2, wiper' 205, bank contact 208, conductor 217, conductor 369, contact 372, armature 371 to generator G3. Relay 377 is designed to be inoperative to the varying current traversing telephone T2 with its receiver on the switch-hook from source G3, but to be operative from direct current, as will traverse the circuit traced through the calling telephone T2 with its receiver off the switch-hook, and therefore, relav 377 will actuate and lock its out side winding to contact 386, spring 354 to grounded lower spring of off-normal set 0Y3. This will also apply ground now on conductor 387 to the inside. terminal of the lower winding of relay 378. The circuit described from armature 375 through the connector A2 and telephone T2 and back through the connector A2. and armature 371 can now be traced from armature 375, contact 388, conductor 389 and to the upperwinding of relay 378. and from armature 371 to conductor 379, lower winding of relay 378, conductor 387, contact 386, spring 354 to ground on the lower spring of off-normal set 0N3, causing relay 378 to actuate. .It

will be manifest that a divided circuit path.

from conductors 369 and 370 exists including conductor 373, condenser 567, ringer 567' and conductor 374, so the said ringer 567 will operate, of course, periodically shunted by armature 565 and its make contact corres onding with the code bells, as set forth. bviously, a plurality of ring.- ers as 567 may be similarly connected in multiple relation between conductors 373 and 374, .The ringer 567 manifestly supplements the gongs 516 and 517.

In this connection it is manifest that it is not necessary to have a signaling current supply source G3, and that therefore the conductor leading to the upper terminal of G3 may be run direct to ground. The only changed operative effect would be that bell 567' would not be rung and no inductive tracing of the ringing current would be projected to the calling party, though periodic disturbances corresponding with the closure 1 of armature 565 would be discerned.

Returning for a moment to relay 377, which actuated consequent upon connector A2 seizing code-connector Fig.- 3' incident to the response of the called party, the ringing current source G3 was disconnected from armature 371. Ground was removed from conductor 353 which allows relay 559 to deactuate, making the code-transmitting equipment availablefor manual control by the attendant and, as will appear presently, also available to other calling parties who may initiate a code-call from a telephone. By reason of armature, 341 attracting, relay 343 'will deenergize and deactuate, freeing contacts 503 to 505 from conductor 344, and causing its armature 345 to retract from contact 346 and unground conductor 347 causing relay 541 to deactuate and open the primarystart circuit of the motor M. Should the rotating arm 501 happen to be at its normal angular position at this instant, the lower set of contacts of off-normal set 0N5 would be opened, and therefore the supply current to the motor M would be opened and the arm 501 would, therefore stop revolving. However, if the arm 501 were in the process of revolving, in its off-normal position, and that the lower set of contacts of off-normal set 0N5 would, therefore, be engaged, the prin'lary-start circuit of the motor would be maintained closed, and this would endure until the arm 501 reached its normal angular. position, whereat the said lower-set of contacts of off-normal set 0N5 would disengage, and open the current supply to the motor M, causing it to cease rotating. The lower armature of relay 377 attracting from its contact 362 prevents any ground coining from grounded contact 560 as mi t be transmitted by another code-connector, as

code connector shown in Fig. 4 for example, as will appear might, in normal operation, cause relay 555 to actuate, and apply ground to the release magnet Re3 falsely over the path described fromgrounded contact 560.

Assume that at the time relav 378 actuated as described, the calling telephone T was on the switch-hook, it having been replaced there by the calling party, after he .initiated the code-calling. and the code-calling was, therefore, transpiring,a circuit can now be traced from generator G3, contact 390, contact 311, conductor 91 over the described circuit path to telephone T (the receiver of which is on the switch-hook) through the condenser 92 and the signal bell 93, to the conductor 25 and over the traced circuit to conductor 309, armature 308 conductor 307, contact 306, and its engaged armature, inside winding of relay 391 to battery. The signal bell 93 at the calling telephone T will ring responsive to the signaling current derived over the latter described circuit path. The calling subscriber will respond in the usual manner by removing the receiver from the switch-hook, whereupon the last describe .l

circuit Will become conductive through the receiver. Relay 391 isso designed that it is inoperative to signaling current of the character emanating from the source G3, but

.it is susceptible to direct current as will traverse the circuit upon its conductive clo- .sure consequent to the removal of the rethe removal of the receiver from the switch- 1 hook at calling telephone T. A telephonic circuit now exists from the calling telephone T over the described path to conductors 91 and 309, including the responding telephone over the circuit from contact 392, conductor 379, armature 371, contact 372, conductor 369, bank contact 208, wiper 205, over the described path through the responding telephone to wiper 206, bank contact 209, conductor 212, conductor 370, armature 375, armature 376, contact 388, conductor 389, armature 308 to conductor 309.

At the time relay 391 actuated its'armature 393 attracted, locking the outside winding through off-normal contact 354 to the lower grounded spring of ofl-normal set 0N3; At the time current was being projected from grounded generator G3 to actuate the bell 93 of the calling telephone T,

before relay 391 actuated, wherein the circnit was completed through the inside Winding of relay 391 to battery, a tracing, received inductively from the inside winding ofv relay 391, was audible to the party at the responding telephone T2 over the following circuit path: battery to outside winding of relay 391, armature 393, and its resting contact, condenser 394, resistance 395, conductor 379, over the described path through the responding telephone to conductor 389, through the upper winding of relay 378 to battery, and upper winding of relay 303 to ground from said conductor 389. The said tracing, audible to the responding party, indicates to him that signaling current is being projected to'ring the bell 93 at the calling telephone and that he must therefore await a response from a calling party though he himself responded.

Assume now that a conversation ensues between the calling and the responding party and that the calling'party replaces the receiver on the switch-hook at telephone T while the responding party is still holding his receiver. Relay 303 will denergize and deactuate, following by relay 317 its period thereafter. Slow-releasing relay 396 is energized consequent to the first off-normal movement of the code-connector Fig. 3, its winding deriving ground through spring 354: and the lowermost armature of relay 317. Due to its slow-release characteristic, relay 396 will remain sustained a period after relay 317 deactuates. A circuit can now be traced from the winding of the release magnet Re3, spring 360, armature 396, armature 397, armature 398 to grounded contact 399. Thus, the path described including contact 399 occurs only if the calling party at telephone T has replaced the receiver on the switch-hook and then responded to the called party, at telephone T2, and after .the telephonic connection with telephone T2 again replaces the receiver on the switch-hook before the party at telephone T2 replaces his receiver on the switch hook. Were relay 396' and the associated circuits not provided. the release under the last assumed condition would take place only upon the party at telephone T2 replacing his receiver on the switch-hook, whereupon the path from the winding of the release magnet Re3 is established through spring 360. lowermost. armature of relay 378 to grounded armature The release magnet Re?) will actuate, and remembering that conductor 301 is now grounded dependent upon armature 82, of relay G in connector A, the release magnet Re3 will lock and remain locked until the said ground is-removed from conductor 301, as described hereinbefore. At the time the release magnet Re3 actuated, it opened the energizing circuit of relay G at contact set 367, as described, hereinbefore. Relay G will therefore deactuate its period after the memes 82, relay B will deactuate, completing an operative circuit for the release magnet Be as before described, resulting in the connector A being restored to normal.

It will be assumed that the code-connector Fig. 3 has been seized by connector A as set forth the code-connector is thereafter caused to be stepped-otf-normal, but not in a rotary direction. at least not having seized a set of code-bank contacts and that the calling party replaces the receiver on the switch-hook at telephone T. Relay 356 will actuate and lock as before set forth, whereupon a circuit will be established from grounded armature 345, armature 397, armature 396, ofi-normal spring 360 to the winding of the release mag net Re3, causing the shaft of code-connector Fig. 3 to be restored to normal and locking the release magnet Re3 as before described until the ground is removed from the test conductor 301 by reason of relay G in connector A deactuating resultant to armature 367 opening its energizing circuit.

Assume that instead of the calling party at telephone T replacing the receiver on the switch-hook, while'the responding party at telephone T2 held his receiver, that the responding party at telephone T2 replaced his receiver on theswitch-hook while the calling party still retained his off the switch-hook.

Upon the responding party opening the described circuit including the winding of relay 378, resultant to his replacing his re ceiver on the switch-hook, relay 378 will deactuate', closing a circuit from the winding of release magnet Re3, spring 360, lower armature of relay 378 to grounded armature 365, causing the release magnet Re3 to actuate and look as before described, restoring the code connector Fig. 3 to normal. Connector A. will release to normal as before set forth, consequent to the .actuation of the re lease magnet Re3. Thus it is manifest that while the connector A is held, dependent upon the actuation of the release magnet Re3 in the code connector, the code connector receives its busy ground existing on conductor 301 and bank contact 18 from the connector A. Heretofore in the art so far as I am aware, the controlling switch has applied the busy ground rather than the dependent switch, as in the present invention.

Refer back to the assumed condition wherein the calling party had caused the code-calling to transpire and had thereafter, before attaining the response of the called party, replaced the receiver on the switch-hook. It will be assumed now that the called party responds as before set forth, but that the calling party has possibly left his telephone, or in any event, no response is made at the .calling telephone T to the sounding of its signal bell 93, consequent to the responding party obtaining telephonic connection with outgoing conductors of the code connector Fig. 3 in the manner before detailed. The responding party after a time, replaces the receiver on the switchhook of telephone T2 and causes connector A and code connector Fig. 3 to be restored to normal as follows: Relay 378 restoring (hearing in mind that relay 39-1 is normal) a circuit may be traced from the winding of the release magnet Re3, spring 360, armature 396, armature 397, to grounded armature 345, it being remembered that armature 345 retracted consequent to relay 377 actuating upon the responding party removing the re ceiver from the switch-hook of telephone T2. It will be obvious that the release magnet Re3 will actuate followed by the actuation of the release magnet Re of connector A. Consequent to the said restoration of the codeconnector Fig. 3 wherein relay 338 deactuates and opens the leading-in path at armature 37 5 and at contact 372, the path includin g the winding of the relay in connector A2 corresponding to G in connector A is opened. Thus, connector A2 will be restored in a manner as hereinbefore described with reference to its like connector A. I

It will be observed that in view of the code-connector always releasing before its cooperating connector A removes groun from the bank contact engaged by'its wiper 45 that there will be no lapseof ground potential on conductor 380 and its attached i bank contacts incident to a release functioning and that therefore the only times the said attached bank contacts and the said conductor 380 do not constitute ground potential are the conditions set forth wherein relay 356 is actuated, or relay 303 is actuated after the seizure of the leading-in conductors of code connector Fig; 3 by conangular position at which time the code transmitting device in Fig. 5 is free and is subject to seizure by a co-operating 'code-.

connector as Fig- 4,'for example, or may be controlled by themanual setting of the code transmitting device through the agency of plug 513 singly or in plurality as has been adverted to.

It will he ififnifeskthat as long as the code-connector Fig. 3 is in engagement with a set of bank contacts, 332 to 336 exampled herein, lam 533 will glow, and that the attendant wil therefore, know that the code transmitting equipment is out of her control and that the indexed .code-connector is in control of the code-transmitting device and that the specific code-call indicated by the particular lamp is transpiring.

'It was stated at the outset that a greater plurality of connectors, such as A and A2, were in common access to the code-connector Fig. 3, and it may be added here, in similar access to the code-connector Fig. 4, as will appear presentlv. With "this in mind, we will now assume that one of these connectors, not shown, has gained seizure of the code connector Fig. 3, in the manner described, with relation to'the connector A, controlled by a calling party. Further, that the responding party has'gained telephonic connection with the calling party through a second connector as A2, not shown, in the manner set forth hereinbeforewith relation to telephone T2 and connector A2. 7

Under the above assumed condition connectors A and A2 and telephones T and T2 are in normal condition. Code-connector Fig. 3 and the two connectors not shown are in co-operation and the calling and the called parties are in telephonic communication. Under this condition there will be ground potential on bank contact 48 and d multiples thereof, and bank contact 207 and multiples thereof. It will be clear presently that a round now (and does normally) exists on ank contact 220, conductor 221, and

bank contact 94 and multiples thereof.

Itwill now be assumed that party at phone T desires to gain communication with the party having the code-call to two bells. He will initiate the call as before set forth, and call telephone number 39 as in the before exampled instance. However, since bank contact 48 now constitutes ground potential, and as will appear presently, bank contact 64 constitutes battery potential, the connector A will, upon its wiper engaging bank-contact 48 be caused to automatically rotate its wipers so that wiper 45 will engage bank contact 64 and seize in a manner as hereinbefore fully set forth. The described circuitpath traced from the calling telephone .T to the wipers 18 and 19 will now be completed from wiper 18 to bank contact 95, conductor 96, contact 401, conductor 402,

conductor 403 to the upper-winding of relay 404 and from the lower winding of the lattele-.

ter relay through contacts 405, spring 406,

- armature 407, conductor 408, bank contact 97 to wiper 19; relay 404 actuating, applying ground on its armature 409 to the winding of slow-releasing relay 410, causing it to actuate. The calling party will now transmit digitl'in the manner as before described, whereupon relay" 404 will deactuate and reactuate one time, transmitting a ground impulse from armature 409, contact 411, armature 412, winding of slow releasing relay 413,

through relay 41.3 will cause it to attract its grounded armature 420. into engagement with its coperating contact and apply ground to the winding of the private magnet P4, causing it to actuate, preparatory to releasing the side-switch wipers 414 and 421, upon its deactuation, permitting them to move into their second positions respectively. This occurs upon the deactuation of relay 413, its period after the deenergization of the vertical magnet V4. following the current impulse.

The calling partly will now transmit digit 2 in the manner as before described, whereupon relay 404 will deactuate and reactuate two times, transmitting a series of two impulses over the described circuit, including the winding of relay 413, winding of the rotary-magnet R4 to side-switch wiper 414 (now in second position) to battery. 'Relay 413 will actuate as before, and due to its slow-release characteristic will sustain until its period has expired following the last impulse of the series. The same functioning of the private magnet P4 ensues as before upon the retraction of armature 420, permitting the side-switch wipers 414 and 421 to move into their third positions respectively. Resultant to thedescribed energization of, and the operation of the rotary magnet R4 the wipers 415 to 419 are caused to be driven two rotary steps engaging bank contacts 422 to 426 inclusive. However, bank contacts 424 and 425 have no operative purpose being disassociated from the circuits.

Upon the side-switch wipers 414 and 421 advancing into their third positions respectively, a circuit path may be traced from ground on contact 427, side-switch wiper 421, winding. of relay 428, side-switch 414 to battery; relay 428 actuating. A circuit path can now be traced from the winding of relay 429, armature 430, to grounded armature 431; relay 429 actuating, wipers 415 to 418 to conductor 344. Also a circuit may be traced from conductor 344,

wiper 416, bank contact 423, conductor 432, conductor 349, to contact 504, and from conductor 344, wiper 415, bank contact 422, conductor 433, conductor 350 to contact 505. Ground on armature 434 will be applied to conductor 435, conductor 347 to the winding of relay 541, causing it to actuate. A circuit path my now be traced from grounded armature 431, armature 436, wiper 419, bank contact 426, conductor 437, to lamp 538, cansand applying masses ing it to glow, and therefore, indicating to the attendant that the code transmitting equipment is under operative control of the code-connector Fig.4 and that it is transmitting series of two bells as indicated by the specific lamp. However, it will be noted presently that upon the response of the called party that armature 431 attracts and removes the ground applied to the wiper 419 and to the lamp 538, whereupon it will extinguish. That is, the lamp 538 will be caused to glow from the time the code-sending eguipment is seized until a response is obtaine from the called party or the codeconnector Fig. 3 is caused to restore.

At the time bank contact 64 was engaged by wiper 45 the said bank contact constituted battery potential, having received it through resistance 440 and conductor 441. However, incident to he seizure of the said bank contact connector A causes its wiper 45 to change the said battery potential to ground potential as hereinbefore set forth. Also, ground potential existed on bank contacts 220 and 94, received from grounded armature 442, armature 443, armature 444, conductor 445 and conductor 221. This ground potential applied over conductor 445 is changed'to battery potential incident to actuation of relay 404 described. The conductor 445 traced to armature 443 is now applied through resistance 446 to battery. Thus, the leading-in conductors (441, 96,

and 408) to Fig, 4 cannot now be seized by a second connector. The leading-out terminals 'areseizable having been unguarded by the change from ground potential on conductor 445, similarly to the functioning'of Fig. 3 described. At the time conductor 441 became grounded this ground is communicated to armature 447, conductor 448 to conductor 353 and over the before described path to the winding of relay 559 causing it to actuate to disassociate the plates 507 to 512, thus guarding the code transmitting equipment against intrusion by the attendant through the agency of plug 513.

From the foregoing it will be manifest that until relay 377 (in Fig. 3) actuated, after the seizure of the code-connector, a busy ground is applied to the leading-in test conductor of code-connector Fig. 4 by way of contact 352, conductor 353, conductor 448, armature 447 conductor 441, conductor 221 to bank contacts 64 and 225 and multiples. This is to insure that but one codeconnector can be in a seized condition if not responded to by the called party; that is to say, but one code-connector can have its wipers in circuit continuity with conductor 344. Thus, when a connector has'seized a code-connector and the code transmitting equipment is operatively functioning due to a code-connector having initiated a code-call the other code-connector is rendered busy loo ' leading to the minus pole of source Ge. Relay 546 will thus actuate and against seizure by a connector. It will appear presently that if the code-transmitting equipment is operatively functioning due to a code-call having been initiated by the attendant through the agency of plug 513, both code-connectors Figs. 3 and 4, are rendered busy against seizure by a connector; this condition. enduring until the plug 513 is disassociated from the plates 507 to 512;;

Recapitulating, we now have lamp 538 glowing, relay 541 actuated, and contacts 504 and 505 attached to conductor 344. It will be remembered that the actuation of relay 541 initiated the rotation of the motor M (relay 576 being normal). As arm 501 engages contact 502 and 503 there will be no operative efi'ect resultant thereto, as these contacts are unattached. However, upon the arm progressing and engaging contact .504, a circuit may be traced from the plus pole of the supply source Ge, through the winding of relay 546, arm 501, contact 504, conductor 349, conductor-432, bank contact 423, wiper 416, conductor 344, armature 543 to conductor 542 leading to the minus pole of the supply source Ge; relay 546 actuating and causing the gongs 516 and 517 to sound as set forth hereinbefore. Upon the wiper 501 progressing to and engaging contact 505 the circuit traced fromthe plus pole of the supply source to wiper 501 will be continued to contact 505, conductor 350, conduc tor 433, bank contact 422, wiper 415, conducior 344, armature 543, to conductor 542 the supply cause the gongs 516 and 517 to sound as before. Upon'the wiper 501 advancing and engaging contact 506 the functioning of drive magnet D5 will ensue as before set forth to advance wiper 521.

Assume now that the called party removes the receiver from the switch-hook of a con venient telephone and initiates the call, as

described hereinbeforefwith relation to the responding party, and dials telephone number 28 as before, causing connector A2 to step up and rotate. its wipers to the bank contact set corresponding to bank position 28. Bearing in'mind that-bank contact 207 engaged by wiper 60 constitutes ground potential due to the assumed telephonic service established through code-connector Fig phone T2 will thus be continued from armature 450 to conductor 465 and to the lower winding of relay 466, and fromthe upper winding of relay 466 to conductor 467 and to armature 454; relay 466 actuating. A lock- 1ng circuit for relay 451 will be established through its armature 468, off-normal spring 461 to grounded spring 462.

Bearing in mind that the calling party is assumed to be holding the recelver off the switch-hook .at telephone T and thattherefore relays 404, 410, 428, and 429 are actuated, a circuit can now be traced from leading-in conductor 96, contact 401, conductor 402, armature 457, inside winding of relay 458 to battery and from leading-in conductor 408, armature 407, armature 459 to the grounded signal current source G4. Relay 458 is designed to be inoperative to current projected from the signal current source G4 under the condition, for example, of the receiver at calling telephone T being on the switch-hook but that it will be op-' 462. The telephonic circuit traced from thecalling telephone T to leading-in conductors 96 and 408 will now be joined through contacts 463 and 464 to conductors 467 and 465 respectively, which latter have been described as including the responding telephone T2, so that the calling and responding telephones are in telephonic connection. Under the assumed condition code-connectors Fig. 3 and Fig. 4 are linked in two independent estab lished telephonic connections, and in view of the hereinbefore descriptions are guarded against seizure through their leading-in conductors by virtue of bank-contacts 48 and 64, and 59 and 225 respectively, and multiples thereof,'constituting ground potential, and

that they are further guarded against seizure through their leading-out conductors by virtue of bank contacts 102 and 94, and 207 and 220 respectively, and multiples thereof, constituting ground potential.

At the time relay 451 actuates and its armature 431 attracts, relay 429 will deactuate. Also'upon armature 447 attracting, the described ground applied from conductor '441 through said armature, conductor 448,

conductor 353, contact 558 to the Winding of relay 559 will be opened, and relay 559 Wlll deactuate, thus enabling the attendant 

